The sialylation of carbohydrates is catalyzed by sialyltransferases (sialylTs) and trans-sialidases. During the biosynthesis of glycoconjugates, enzymes belonging to the glycosyltransferase family (including sialylTs) catalyze the transfer of a monosaccharide unit from an activated glycosyl donor to an appropriate acceptor molecule. In the case of sialic acid (NeuAc), the activated donor is considered to be NeuAc that is β-glycosidically linked to the aglycan cytidine 5′-monophosphate (CMP) to form CMP-NeuAc (1). In contrast to other activated nucleotide sugars, CMP-NeuAc contains a monophosphate. This activated sugar is also unique since it forms α-glycosidically linked sialic acid residues in nature (2).
While CMP-NeuAc is considered to be useful as a sialic acid donor in sialylation reactions, because it is currently prepared by chemical synthesis, its use as a sialic acid donor is not cost efficient. Thus, there is an ongoing, unmet need for a cost effective method for the preparation of CMP-NeuAc.